<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .container{
      width: 100%;
      height: 300px;
      background-color: bisque;
      position: relative;
    }
    .position-box,.transform-box{
      width: 100px;
      height: 50px;
      line-height: 50px;
      text-align: center;
      background-color: red;
    }
    .position-box{
      position: absolute;
      left: 0;
      top: 20px;
      animation: posi-ani 3s ease infinite alternate;
    }
    .transform-box{
      animation: trans-ani 3s ease infinite alternate;
    }
    @keyframes posi-ani{
      100% {
        left: 700px;
      }
    }
    @keyframes trans-ani {
      100%{
        transform: translateX(700px);
      }
    }
  </style>
</head>
<body> 
  <div class="container">
    <div class="position-box">left</div>
  </div>
  <div class="container">
    <div class="transform-box">transform</div>
  </div>
  <script>
    let container = document.getElementsByClassName('container')[0]
    // let style = window.getComputedStyle('.container')
    // console.log(style)
    function blockFunc() {
      var arrs = new Array(10000 * 10000)
      console.time('for')
      for (let index = 0; index < arrs.length; index++) {
      }
      console.timeEnd('for')
      console.time('forEach')
      arrs.forEach((arr,index, origin)=>{
      })
      console.timeEnd('forEach')
    }
    var obj = {
      name: 'lu-lu',
      age: 20
    }
    console.log('name' in obj)
    console.log('name1' in obj)
  </script>
</body>
</html>